Long Term Durability of a Lubricant-Infused Surface for Dew Harvesting

Abstract

Hydrophobic, lubricant-infused surfaces offer enhanced potential for dew harvesting compared to bare metal substrates due to their water repellent nature. Most of the studies to date examine the condensation effectiveness of the nonwetting surfaces over a short duration and have not considered the durability or performance of the surfaces over extended periods. To address this limitation, the present study experimentally investigates the long-term performance of a lubricant-infused surface subject to dew condensation for 96 h. Condensation rates as well as sliding and contact angles are measured periodically to examine the surface properties and water harvesting potential over time. Due to the narrow time window in which dew harvesting can be conducted in application, the additional collection time gained by shedding droplets at lower nucleation times is explored. It is shown that three phases occur in lubricant drainage, which affect performance metrics relevant to dew harvesting. The first 24 h of condensation induces drainage that has little effect on the adhesion of droplets to the surface and on the additional collection time. The next phase, from about 24 to 72 h, showed steady drainage and a steady decrease in performance. The final 24 h, from about 72 to 96 h of operation, was seen to have little added effect on drainage and therefore on the performance metrics. The study bears significance in the design of surfaces for long-term use in practical water harvesters.